Interference reducing radio receiving system



Nov. 11, 1952 L. COHEN 2,617,926

INTERFERENCE REDUCING RADIO RECEIVING SYSTEM Filed July 29, 1948 i :5 m Q? *R 19 20 7- INVENTOR. 9 LOUIS sci-KEN ATTORNEY Patented Nov. 11, 1952 UNITED STATES PATENT OFFICE INTERFERENCE REDUCING RADIO RECEIVING SYSTEM Application July 29, 1948, Serial No. 41,205

14 Claims.

This invention relates to the art of radio signaling and has for its object the elimination or substantial reduction of foreign electrical disturbances, including those caused by atmospheric discharges, in the reception of radio signals.

Another object of the invention is to provide a simple device which can be used with most radio receivers to eliminate or substantially reduce the effect of foreign electrical disturbances in the reception of radio signals.

Further objects of the invention are in part bvious and in part will appear from the detailed description hereinafter.

The present invention makes use of a wave conductor such as disclosed in Patent 2,415,810 issued to applicant on February 18, 1947, or in applicants application 769,216, filed August 18, 1947, which matured into Patent 2,558,339 on June 26, 1951, but embodies the same in a simpler circuit than there disclosed.

A wave conductor is a conductor having such distributed inductance and capacity that its electrical length is a substantial fraction of the wave length of the desired signal, thereby permitting a substantial wave development thereon.

A convenient form of Wave conductor as described in said Patent 2,415,810 is a solenoidal coil wound with a sufiicient number of turns of wire, and with its distributed capacity increased by a metal plate adjustably located in proximity thereto. Although the patent discloses a flat plate, the plate may obviously be shaped to conform closely to the shape of the solenoida'l coil. Numerous mechanical devices may be used to provide an adjustment of the distributive capacity by varying the separation of plate and coil. Instead of using a metal plate, the solenoidal coil may be enclosed in a metal cylinder, and the distributed capacity varied by moving the coil in or out of the cylinder. Preferably, the cylinder should be split so as not to .produce the effect of a shorted turn. Instead of a soleno-idal form of coil, a conically shaped coil may be employed with a conically shaped metal cap conforming closely to the exterior of the coil and capable of being displaced relative theretoalong the aXis of the cone or any other convenient form of plate and coil may be employed which permits ready variation of the distributed capacity between them.

Or the coil maybe Wound in the form of a flat spiral and associated with a flat circular metal plate adjustably positionable with respect thereto, as by hinging the flat coil and plate together at the periphery.

In addition to or in place of the adjustment in the distributed capacity, the electrical length of the wave conductor may be varied by varying the amount of inductance included in the circuit. Thus, instead of using a simple inductance, a number of separate inductances may be employed, together with a switching arrangement which will connect a desired number of inductances in series in the circuit, or the coil may be tapped and an appropriate switch employed to connect a greater or lesser part of the coil into the circuit. Or the inductance may be separated into two portions Whose mutual inductance may be varied, thus varying the total self-inductance of the system.

The amount of wire used may be reduced by employing powdered iron cores or other forms of iron cores with low hysteresis losses such as employed in the well-known permeability tuning arrangements. By varying the position of the core, the inductance may be tuned in the same manner as is usual with permeability tuners.

Without limiting the invention to any particular theory of operation, it is believed that basically the operation of the present invention as well as those described in said Patent 2,415,810 and application 769,216 may be explained in the manner set forth below. The circuit of the invention has been analyzed mathematical-1y and the theory set forth here is based on such analysis. Without burdening the specification with the details of such mathematical analysis, the basic principles appear to be these:

When an electrical disturbance acts as an oscillatory circuit, for example, a wave conductor and its associated circuits, it sets up oscillations of a frequency determined by the parameters of the circuit system. The phase and amplitude of the current produced depends on the applied voltage, its manner of application, and the parameters of the circuit system and may be represented by the formula where E is the applied voltage and d (f) is a function of the frequency as determined by the circuit parameters. If the disturbing energy is ap-' frequencygand: thus balance out the effect of in- I terfering impulses without balancing out the desired signal.

The present invention provides a snnple and newer means of applying this theory to' existing radio receiving sets without .any modification of their structure.

In the drawings which set vforthatypical-diaw grammatic circuit systems emhody netthexp e a:

ent invention:

Fig. 1 is a diagrammatic representation-of-a simple form of my invention.

Fig. 2 is a modification embodying a separate control'of energy transfer from a supplemental I antenna.

Figiifir-is. ardetaiiimodification-of the. -separate"- controltoffi qfi I.

Fi xarisraffurthen modification of the control.

Pigtails a; modificationemploying permeability tuningnrn Figafi is .amudification usingga singlet antenna.

place.

Fig 9. is :a lfulrther; rmodificationfiofthe device a of El'ggii.

InrEig-i 1,; I.v represents a simple antenna or. en: ergy collector; 2 is a wave coil or wave conduc-m tort. 3 iisa 'zmetalqplate; adjustably; positionable withzrespeot {thereto-to wary; the distributed ca- :2 andztherebyrvary its effective electricaldength 4-. :is the rantennarterminalof aradio:

reseller? 5 :is :a'; second. antenna: or. ener y ;.co11ec-;

. also through the plate 3. -The.variable condenl-;

pacity :of coil tom-which mayebe :uSBd fbO, obtain; improved re-' sults. The waveeoonduotor72:.and the;associated plated; mayzbenoirtheitype shown in said Patent 2,41-55810rfih011ah1zanytof sthei other modifications discussednbovemayzbe used insteadv When the inductance .iSJCOHIIGC'bBd in-qiseries. between. the

antenna I, and ithe -..antenna;;terminal *1 4 of any standaiid receiueniihave found that'substantial 1 reductiominrtheaeffectsiof Tinterfering electrical impulses is. obtained ;simply; by adjusting the distanaerseparationsof; plate; 3 from coil 2.- In many casesnthezcoim'and platea'pickup; suflicient 'interfering energy so that.nos{additionalantennav is needed to makev possible substantial balancin outtiofcinterferingz signalrz. Generally;- however; bettemresultsrare z-obtainedwifia ;second::antenna 5 is connectedto-the metaliplate13; The:antenna lly comparable injleng-th :to antenna 1, 1

5 1 ne a.

butsthe-r .l ionshipisnot critical Theaadjustment of platefii, .it to be varieslooththe: effective .length .of: the wave 'con' ductor 2 as well as the effective energy..trans.-

fer from antenna 5 to. the,,-oscillatory circuit via the distributed capacity between plate 3 and coil 2 -Tliough the senergy; :transfer and the 'efiective electrical length ares-parameters which may :be

variemindividually'tonobtain a condition :where their Joint variationiby movementsofyplate 3 is very efiectivetto.producaa conditiongw r s stantiall-iiiallnoise iseliminated.

In'. some cases, especiallyvwhereu-the "whole .de-.. viceisjshielded so .that. the tuning plate. 3 does tobservedt In that case it is especially desirable to provide means for varying the energy supplied by the 2nd antenna. Such an arrangement is shown in Fig. 2 where in addition to the variably positionable 5 plate 3 .forxtuning-the coil, asecond plate 6 is provided in fixedcapacitative relation to coil 2 for coupling antenna 5, the whole device being encased in grounded metal case 8. The amount of energy transferred is effectively controlled by -varying condenser 7 thus by-passing more or less energy'to ground.

Fig-,3 shows a modification where a variable high resistance -9 is substituted for the capacity 1 ;to:regulate.sthe z by-pass from antenna 5 to l5.i round'.-..

Fi'gAshows a further modification wherein the variable. capacity] .is placed in series with antenna 5 and plate 6, but this is not as effective asthe other-arrangements.

It is understood, of course, that the various means :for, controllinggthe energy transfer. shown in Figures 2, 3,-and' 4 mayalsobe employediwhere the'antenna 5 couples directly t the tuningplatm 3 as in :Fig. .1, and thus make it possible to more closely controlthe balance than is possible in Fig. 1 where the energy transfer from antenna 5 .is controlledsole'ly by-tuning plate3;

Fig.5 .is a further. modification showing the use" of permeability tuning; Coil-2 is tuned byyinsertion or withdrawal of thelow-hysteresis iron core 13. The secondantenna 5 is coupledtocoil 2 by-plate 6 fixed in capacitative relation thereto. Energy transfer from antenna'i is regulated by variable capacity '5 controlling the amount of bypass to grounds In place of. capacity 1, a variaser H serves-to control distribution' of energy'between. the twoepathsh A second variable con-=- denser l2 may goptionallybe employed in the 4 otherbranch of, the antenna lead. O

antenna l is connected-to the rotorl3 of aacondenser-having -a split stator'.comprising a halfvaries-.thedistribution of energy between coil .2

and-plate 3.

terminal 4 of aradio receiver;

Figure 9 is a modification ofthe-devioe shown: 1 in Fig. 8 whichis useful with receivershavinga primary serial coil coupled to a tuned input cir;-i: cuiti In this modification, R is a radio=-receiver:i. having, an .aerialcoil. l9 connectingto antenna terminal 4 and in inductive relation to-secondaryy .70 20 which forms-a tunedcircuit with-condenser 2l.' Terminals 22. and 23 connect to the grid and filament respectively of -a detecting or amplifye ing tube. .Antenna l connects to coupling strip l6 and antenna terminal 4 to coupling-strip. 11,

: exactly. as inFigls. .An additionalcouplingstrip ble. resister may be usedas .shown-in Fig..-3,0r

Fig." 6 is 'a modification usingasingle antenna;

A similar resultis obtained in Figs? wheregthe l4 connected-to plate 3 and .ahalfzl5 connected-- to coil. 2. Changing the position of thelrotor Although in most: of the previous figures the" coil Z-has beenshown as connected directly in 'se-:

ries inthe lead from antenna- I, this coupling; 50 may: be inadecapaoitatively as shown in;Fig. 8. 1 l6 and I1 are-metal strips in .capacitative'rela-m tion, tocoil 2 and adjustable both alonggthe; lengthzthereof and with respectto their-separa tion therefrom thereby making possible-a varia' s 5 tion in the length of coil'included in the antenna circuit, and theamount of energy transfer; Stript it connects to antenna 1 and strip 1 I toantenna' 13 connects to the grid side of the tuned input of the receiver B. This modification, by appropriate adjustment of the position of the various coupling strips, including an adjustment both as to position along the length of the coil and distance separation therefrom of strip it gives very ood results without the use of the second antenna 5, which, however, may also be used in this modification.

While the invention has been described as embodied in specific forms for purposes of illustration, it should be understood that the invention is not limited thereto, since various modifications will suggest themselves to those skilled in the art without departing from the spirit of the invention, the scope of which is set forth in the annexed claims.

I claim:

1. A device for reducing the effect or" interferenere'y associated with desired signal energy a radio receiving system comprising a radio receiver connected to an antenna solely through the intermediacy of a wave conductor comprising said wave conductor, means for connecting one point on said wave conductor to an antenna, means for connecting another point on said Wave conductor to the antenna terminal of a radio receiver, an energy collector, distributive capacity coupling means for applying mixed signal and interfering energy from said energy collector to wave conductor, and means for varying the electrical length of the wave conductor to reduce the effect of said interfering energy on the reception of the desired signal.

2. A device as in claim 1 including means for 1 varying the relative amounts of interfering energy transferred to the wave conductor directly from the antenna and through the distributed capacity coupling means.

3. A device as in claim 2 including means for lay-passing to ground a desired proportion of the energy applied to the distributed capacity coupling means.

4. A device as in claim 3, wherein the amount of ener y lay-passed to ground is varied by means of a variable capacity in the by-pass lead to the round.

5. A device as in claim 3, wherein the amount of energy by-passed to ground is varied by means of a variabl resistor in the by-pass lead to the round.

6. A device as in claim 2 including a variable capacity connected between the distributive capacity coupling means and a means for connection to an energy collector.

7. A device as in claim 2, wherein a metal plate adjustably positionable with respect to the wave conductor serves both to vary the energy trans-- ferred through the distributive capacity coupling means and to vary the efifective electrical length of the wave conductor.

8. A device as in claim 2, wherein the electrical length of the wave conductor is variable by means of permeability tuning, and including separate means to vary the amount of energy transferred to the wave conductor through the distributive capacity coupling means.

9. A device as in claim 1 including means for varying the electrical length of the wave conductor and means for varying the relative amounts of energy applied to the wave conductor distributively and at a point.

10. An antenna system for reducing the effect of interfering energy comprising an antenna, a wave conductor connected at one point to the antenna, means for connecting a second point on the wave conductor to the aerial terminal of a radio receiving system, a second antenna, adjustable distributive capacity coupling means for applying the energy from the second antenna to the wave conductor, and means for varying the effective electrical length of the wave conductor.

11. In a radio receiving system comprising a radio receiver connected to an antenna through the intermediary of a wave conductor and having a tuned input circuit and an antenna coil inductively coupled thereto, a wave conductor, a metal plate adjustably positionable with respect to the wave conductor and an energy collector connected thereto, an antenna capacitatively coupled to one point on the wave conductor,means to capacitatively couple another point on the Wave conductor to one terminal of said antenna coil, and means for capacitatively coupling a third point on the wave conductor to said tuned input circuit.

12. In a radio receiving system, a wave conductor, an antenna directly connected to one end of said wave conductor, the other end of said wave conductor being directly connected to the aerial terminal of a radio receiver, a metal plate adjustably positionable with respect to the wave conductor to substantially reduce the effect of interfering energy on the reception of desired signals, and an energy collecting means connected to said plate.

13. A device as in claim 12 in which the energy collector is connected to a metal plate in fixed capacitative relation to the wave conductor, the wave conductor and associated plates are enclosed in a grounded metal container, and means to regulate the amount of energy transfer from said energy collector to the wave conductor.

14. A device as in claim 12 in which the metal plate is adjustably positionable with respect to the wave conductor in such manner as to vary both the total amount of coupling between the plate and the wave conductor and the relative amount of coupling between the plate and different points along the wave conductor.

LOUIS COHEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 984,762 Hart Feb. 21, 1911 1,468,049 Taylor Sept. 18, 1923 1,476,691 Cohen et al. Dec. 11, 1923 1,683,847 Roos Sept. 11, 1928 1,857,359 Cohen May 10, 1932 1,872,246 Cohen Aug. 16, 1932 ,967,604 Beverage July 24, 1934 2,051,260 Lesh Aug. 18, 1936 2,054,645 Alexander Sept. 15, 1936 2,271,909 Beverage Feb. 3, 1942 2,415,810 Cohen Feb. 18, 1947 FOREIGN PATENTS Number Country Date 421,564 Great Britain Dec. 18, 1934 

